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blindsight

Junior Member
Registered Member
BoraTas said:
The problem is not limited horsepower. A diesel engine has a higher power density than a nuclear reactor-steam turbine combo. The reactor, steam turbine, shielding, and supporting machinery are estimated to weigh around 1050 tons in the Borei class. (
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) That brings 50k horsepower to the shaft. That is less power density than a low-speed diesel. A nuclear reactor holds no inherent advantage in enabling a deeper dive or higher max speed. In fact, it can be considered detrimental because the extra weight it adds has to be compensated by more volume to keep the reserve buoyancy the same. The problem is how much usable energy you can store in a submarine. That is where nuclear sub shines. High-speed endurance is about stored energy. The comparison of nuclear submarines and conventional ones is a comparison of propulsion systems. Looking at general characteristics is wrong because they are the results of multiple things. Great powers have switched to SSNs because they need open ocean capabilities. This left conventional subs to smaller powers or great powers who needs to defend their shores. That is what led to the current small conventional sub, big nuclear sub paradigm.
The Japanese have switched the lithium-ion because their intent is to use the Taigei class in open oceans and distant areas. For that you need a lot of diesel fuel and good high-speed submerged endurance. Lithium-ion batteries improve the high-speed endurance of a conventional sub by multiple times. And they are rechargeable unlike the AIP system. Diesel fuel is still the densest way of storing more energy in a conventional sub. The low and medium speed patrol endurance of a non-AIP lithium-ion sub would be lower than an AIP sub. Japan is an oddball because of its laws. Other AIP producers are going to use lithium-ion batteries in addition to AIP, it makes more sense.
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I vote for SMR + Li-ion batteries
 
G

gelgoog

Lieutenant General
Registered Member
BoraTas said:
The problem is not limited horsepower. A diesel engine has a higher power density than a nuclear reactor-steam turbine combo. The reactor, steam turbine, shielding, and supporting machinery are estimated to weigh around 1050 tons in the Borei class. (
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) That brings 50k horsepower to the shaft. That is less power density than a low-speed diesel.
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Only if you ignore the weight and volume of the fuel. You also need lots of batteries.

BoraTas said:
A nuclear reactor holds no inherent advantage in enabling a deeper dive or higher max speed. In fact, it can be considered detrimental because the extra weight it adds has to be compensated by more volume to keep the reserve buoyancy the same. The problem is how much usable energy you can store in a submarine. That is where nuclear sub shines. High-speed endurance is about stored energy.
Click to expand...

Exactly, a conventional submarine can't keep going at high speed for a considerable amount of time. That is particularly problematic for long distance patrols. Nuclear fuel is also like a million times more dense per unit of mass than diesel. And you can't operate the diesel engines unless you are surfaced or snorkeling at low speeds.

BoraTas said:
The comparison of nuclear submarines and conventional ones is a comparison of propulsion systems. Looking at general characteristics is wrong because they are the results of multiple things. Great powers have switched to SSNs because they need open ocean capabilities. This left conventional subs to smaller powers or great powers who needs to defend their shores. That is what led to the current small conventional sub, big nuclear sub paradigm.
The Japanese have switched the lithium-ion because their intent is to use the Taigei class in open oceans and distant areas. For that you need a lot of diesel fuel and good high-speed submerged endurance. Lithium-ion batteries improve the high-speed endurance of a conventional sub by multiple times. And they are rechargeable unlike the AIP system. Diesel fuel is still the densest way of storing more energy in a conventional sub. The low and medium speed patrol endurance of a non-AIP lithium-ion sub would be lower than an AIP sub. Japan is an oddball because of its laws. Other AIP producers are going to use lithium-ion batteries in addition to AIP, it makes more sense.
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Japan had the Stirling engine technology in the Soryu and it has enough industrial expertise to make hydrogen fuel cells for a submarine if they wanted to. Honda and Toyota for example have worked on hydrogen fuel cells for at least some two decades. Yet they choose not to. I would ignore Japan's laws as limitations at this point. The Japanese Constitution has been changed significantly enough it doesn't impose much of a limitation anymore as you can see with the Japanese Navy now being able to operate carriers.
 
Dante80

Dante80

Junior Member
Registered Member
Andy1974 said:
Mock up in the desert for DF-21s
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The article you posted is about an AWACS airplane contract. What does it have to do with -presumably navy ships?- mockups for DF-21 "testing"?

You probably wanted to link a different article.
 
by78

by78

General
Various commemorative coins marking events and ships of significance.

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